Am I sinful for not visiting my paternal half-siblings due to the many problems they instigate and their disrespect for those who intervene to resolve disputes, knowing that they do not visit me despite my repeated invitations to them?

Maintaining kinship ties is obligatory, and it is impermissible to sever them even if they sever you. The one who maintains ties is not the one who reciprocates, but rather the one who maintains ties with those who have cut him off. The abundance of family problems and estrangement does not permit retaliation in kind. The reward increases, and Allah grants victory to one whose kindness is met with ill-treatment. The Messenger of Allah (peace be upon him) said: "If you are as you say, then it is as if you are feeding them hot ashes, and you will continue to have a supporter from Allah as long as you remain in that state." You must maintain ties with your siblings by any possible means, such as calling them, sending gifts, or corresponding, and it is not necessary to visit them if that is difficult.